FIELD OF THE INVENTION
This invention relates to elastic supports for supporting stuffing or upholstery of seat or furniture pieces such as beds, divans, armchairs, chairs, car seats and the like, and more particularly to an improved elastic support element or belt of the type referred to and to a textile machine for weaving such elastic support or belt.
The use of elastic belts for supporting the stuffing or upholstery in furniture pieces such as seats, backs, arm rests, backboards, motor vehicle seats and backs, and the like is well known. The elastic belts of this kind at present in use are affected by various disadvantages such as for example a lack of uniform spring suspension because each belt applied to the supporting frame has not the same tension as the other belts which are stretched and applied one at a time, and therefore the more stretched belt "works" more than the other belts and supports alone all the weight of the user, thereby fringing and breaking prematurely and causing also the other belts to fringe and break. These elastic belts have been improved by providing on the elastic threads a spirally wound covering formed of natural or synthetic yarns.
From the Italian Patent n. 955 134 a support of this kind is also known, which comprises an elastic net formed of a net or honeycomb fabric made of rubber threads or the like arranged in the longitudinal or warp direction, which rubber threads are covered with a plurality of spirally wound yarns and preferably crossed in the other or weft direction by non-elastic threads of nylon or cotton or other suitable textile fiber.
However, also this support is affected by drawbacks due to the fact that the plurality of spirally wound yarns, while partially overcoming the drawback of the not-uniform spring suspension, require expensive working operations and the use of a great amount of textile yarn, which makes the spiral winding very expensive.
In an attempt to overcome this drawback, use was made of a yarn spirally wound in one direction and a yarn spirally wound in the opposite direction, but this has not solved the problems that the spiral winding involves. Therefore the elastic threads covered by a plurality of spirally wound yarns, in spite of the precautions taken, lead to tension differences of the covered elastic threads at the time of their manufacture, what gives effect of false twistings and undulations of the elastic support element obtained thereby.
U.S. Pat. No. 4,728,565 improves the above mentioned support element by covering the rubber warp threads by loops formed chain-stitches, mainly improving the resistance and stability of the net.
However, even this last improvement did not reveal itself a perfect solution, because its continuous use brought to a relative shifting between the warp elastic threads and the weft yarn in given points, with a permanent and increasing alteration of the size ratios of at least same of the components of the net formed by said warp threads and weft yarn. This involves an improper reaction of the support belt or element and a reduced life thereof. To try to overcome this drawback, the support elements or belts were impregnated with a latex, but this gives a bed appearance to the product, reduces its resilient features, hinders the passage of air therethrough and rapidly ages the materials contacting the same, in particular the seat foam.